overlay.js

// The error overlay is inspired (and mostly copied) from Create React App (https://github.com/facebookincubator/create-react-app)
// They, in turn, got inspired by webpack-hot-middleware (https://github.com/glenjamin/webpack-hot-middleware).

import ansiHTML from "ansi-html-community";
import { encode } from "html-entities";

const colors = {
  reset: ["transparent", "transparent"],
  black: "181818",
  red: "E36049",
  green: "B3CB74",
  yellow: "FFD080",
  blue: "7CAFC2",
  magenta: "7FACCA",
  cyan: "C3C2EF",
  lightgrey: "EBE7E3",
  darkgrey: "6D7891",
};

let iframeContainerElement;
let containerElement;
let onLoadQueue = [];

ansiHTML.setColors(colors);

function createContainer() {
  iframeContainerElement = document.createElement("iframe");
  iframeContainerElement.id = "webpack-dev-server-client-overlay";
  iframeContainerElement.src = "about:blank";
  iframeContainerElement.style.position = "fixed";
  iframeContainerElement.style.left = 0;
  iframeContainerElement.style.top = 0;
  iframeContainerElement.style.right = 0;
  iframeContainerElement.style.bottom = 0;
  iframeContainerElement.style.width = "100vw";
  iframeContainerElement.style.height = "100vh";
  iframeContainerElement.style.border = "none";
  iframeContainerElement.style.zIndex = 9999999999;
  iframeContainerElement.onload = () => {
    containerElement =
      iframeContainerElement.contentDocument.createElement("div");
    containerElement.id = "webpack-dev-server-client-overlay-div";
    containerElement.style.position = "fixed";
    containerElement.style.boxSizing = "border-box";
    containerElement.style.left = 0;
    containerElement.style.top = 0;
    containerElement.style.right = 0;
    containerElement.style.bottom = 0;
    containerElement.style.width = "100vw";
    containerElement.style.height = "100vh";
    containerElement.style.backgroundColor = "rgba(0, 0, 0, 0.85)";
    containerElement.style.color = "#E8E8E8";
    containerElement.style.fontFamily = "Menlo, Consolas, monospace";
    containerElement.style.fontSize = "large";
    containerElement.style.padding = "2rem";
    containerElement.style.lineHeight = "1.2";
    containerElement.style.whiteSpace = "pre-wrap";
    containerElement.style.overflow = "auto";

    const headerElement = document.createElement("span");

    headerElement.innerText = "Compiled with problems:";

    const closeButtonElement = document.createElement("button");

    closeButtonElement.innerText = "X";
    closeButtonElement.style.background = "transparent";
    closeButtonElement.style.border = "none";
    closeButtonElement.style.fontSize = "20px";
    closeButtonElement.style.fontWeight = "bold";
    closeButtonElement.style.color = "white";
    closeButtonElement.style.cursor = "pointer";
    closeButtonElement.style.cssFloat = "right";
    closeButtonElement.style.styleFloat = "right";
    closeButtonElement.addEventListener("click", () => {
      hide();
    });

    containerElement.appendChild(headerElement);
    containerElement.appendChild(closeButtonElement);
    containerElement.appendChild(document.createElement("br"));
    containerElement.appendChild(document.createElement("br"));

    iframeContainerElement.contentDocument.body.appendChild(containerElement);

    onLoadQueue.forEach((onLoad) => {
      onLoad(containerElement);
    });
    onLoadQueue = [];

    iframeContainerElement.onload = null;
  };

  document.body.appendChild(iframeContainerElement);
}

function ensureOverlayExists(callback) {
  if (containerElement) {
    // Everything is ready, call the callback right away.
    callback(containerElement);

    return;
  }

  onLoadQueue.push(callback);

  if (iframeContainerElement) {
    return;
  }

  createContainer();
}

// Successful compilation.
function hide() {
  if (!iframeContainerElement) {
    return;
  }

  // Clean up and reset internal state.
  document.body.removeChild(iframeContainerElement);

  iframeContainerElement = null;
  containerElement = null;
}

// Compilation with errors (e.g. syntax error or missing modules).
function show(messages, type) {
  ensureOverlayExists(() => {
    messages.forEach((message) => {
      const entryElement = document.createElement("div");
      const typeElement = document.createElement("span");
      // ts-loader will output `error.file` for error file path, not in message
      typeElement.innerText =
        (type === "warnings" ? "Warning:" : "Error:") + (message.file || "");
      typeElement.style.color = `#${colors.red}`;

      // Make it look similar to our terminal.
      const errorMessage = message.message || messages[0];
      const text = ansiHTML(encode(errorMessage));
      const messageTextNode = document.createElement("div");

      messageTextNode.innerHTML = text;

      entryElement.appendChild(typeElement);
      entryElement.appendChild(document.createElement("br"));
      entryElement.appendChild(document.createElement("br"));
      entryElement.appendChild(messageTextNode);
      entryElement.appendChild(document.createElement("br"));
      entryElement.appendChild(document.createElement("br"));

      containerElement.appendChild(entryElement);
    });
  });
}

export { show, hide };